The progress in the box in the bottom left corner of Kobo Desktop was stated as follows (with the time it took in brackets):

"The Hunger Games 1 of 3" (8 mins) (I already have this on my Kobo and finished reading it last week and have synced since finishing so why is it syncing this book??)
"Loading content" (30 secs)
"The War of the Worlds 2 of 3" (30 secs)
"Loading content" (30 secs)
"The Invisible Man 3 of 3" (1 min)
"Loading content" (30 secs)
"The Hunger Games 1 of 3" (1 min)
"The War of the Worlds 2 of 3" (30 secs)
"The Invisible Man 3 of 3" (30 secs)

FINISHED

Why does it scroll through the books twice? Is the first time the book being downloaded from the Kobo website, and the second time it is being added to my Kobo? This doesn't explain why it downloaded The Hunger Games seeing as I did that a few weeks ago already.

Alternatively, I downloaded an ePUB ACSM link from Kobo website, added it to ADE and it uploaded to my Kobo in seconds.

So in summary, any ideas as to why syncing via Kobo desktop take so much longer than uploading via ADE? And why did Kobo Desktop spend 8 minutes syncing "The Hunger Games" when I already had it? (I have the "Reading Life" turned off)